WE DON’T agree with President-elect Donald Trump on much, but we happen to share his view that the Obama administration overreached in trying to rewrite immigration law unilaterally. Still, tough enforcement is one thing; gratuitous cruelty is another. Mr. Trump would be straying squarely into the second category if his immigration crackdown targets youngsters whom Mr. Obama has shielded from deportation since 2012.

Under that program, 750,000 undocumented immigrants — mainly teenagers and 20-somethings who grew up in America and graduated from U.S. high schools — have received work permits and Social Security cards. Most have jobs; they pay taxes, open bank accounts and, for the most part, live productive, law-abiding lives.

It would serve no public policy purpose to pursue this cohort of young people, most of whom were brought to America as children by their parents, and are undocumented through no fault of their own. Half have relatives who are U.S. citizens; roughly a quarter have children who were born here.

To round them up, or threaten them with deportation, would mean hounding families who have lived here for well over a decade. Most of the youngsters are as culturally American as their U.S.-born neighbors; many are building careers that will contribute to their communities. They make no secret of their immigration status or whereabouts, having registered openly with the government under the Obama administration’s program. For Mr. Trump to use that database to target them would be a mistake that would brand his new administration as callous and recast this country as America the Punitive.

Mr. Trump’s worst instincts on immigration were underscored by news that a notorious hard-liner, Kris Kobach, would serve on his transition team. Mr. Kobach, the Kansas secretary of state, has been behind countless crusades over the past decade, many of them thwarted in federal courts, to harass and intimidate immigrants.

Mr. Kobach vowed Thursdsay that the Trump administration would build that “beautiful” wall, and there’s no doubt Mr. Trump has a mandate to do so. It would be a massive waste of money — a $15 billion to $25 billion project that would do nothing to stop visa over-stayers, who represent a third of undocumented immigrants, and relatively little to deter illegal border crossings, already near a 40-year low. No wall is impermeable, and more Mexicans have left the United States than entered since the Great Recession of 2008. And no, Mexico won’t pay for the wall.

But if Mr. Trump wants to squander taxpayers’ funds on a symbol, and fight court battles with American border ranchers who oppose federal encroachment on their land — well, yes, he has a mandate for that.

Likewise, relatively few Americans would oppose Mr. Trump’s pledge to deport undocumented criminals; that’s also Mr. Obama’s policy. Support might decrease if Mr. Trump expands the definition of “criminal” to include minor infractions. That would strip U.S. industries, particularly in the agricultural sector, of valuable workers who are not easily replaced. Opposition would grow further if he attempted to round up millions of migrants who are law-abiding in everything but immigration status; polls show most Americans would not favor such mass deportation.

And surely he would lose most of the country if he goes after the young valedictorians and veterans who in good faith came forward when Mr. Obama offered his first, tailored reprieve. Mr. Trump’s victory grants him license for meaningful enforcement, not malice.